1. Field of the Invention
The invention relates to a process and a device for dehusking cereal grain, especially for removing the husks and/or the seed coats as well as the germ from grain and/or from malted grain and its processing in the brewing industry.
2. Background Information
Before malting or immediately before processing in the brewing process, according to the prior art, grain can be separated while wet and/or dry from the husk and/or from the seed coat as well as from the germ, and thus also be cleaned of original contaminants and/or harmful substances on the grain surface. In previous decades, dry cleaning has become the generally established method. Thus, CH-A-640750 describes a process in which the grains are subject to dry cleaning including scouring and aspiration. Then the grains are wetted and stored in conditioning cells for several hours. After conditioning, the grain is shelled immediately before the first grinding pass. Here the shelling may be preceded by a further conditioning. This is done depending on the degree of shelling and/or the tenderness of the grains following the moistening and conditioning.
It is also known how to polish cereal grains up to the point where they are released from the pericarp and the endosperm is exposed (EP-B-218012). For this the pericarps are removed incrementally in several polishing stages, during which moisture is added to the grains in at least one stage. The moistened grains may also be heated. After the heating, which may be done concurrently with moistening, the grains are dried and cooled. According to EP-B-529843 moistened and polished wheat grains are cleaned once more. This cleaning is a wet cleaning, in order to remove bran particles which are still adhering, especially from the crease as well. The grinding of malt on rice polishing machines is also known.
Similarly known is the scouring of grains to reduce the microflora of the husks/seed coats, as well as the grinding of grains.
Just as familiar are grain grinding machines with a vertically oriented rotor, e.g., according to EP-B-742048, in which the grain to be ground can additionally have air blown through and be moistened with water.
In the so-called PeriTec process, too, the outer cell layers, including the aleurone layer, are abraded away. Wheat is cleaned and moistened in a similar way to conventional processes, however one can omit the use of scouring machines. Before the polishing, moistening is again carried out in a controlled manner. The purpose of this is to release the outer from the inner layers, they then being rubbed away to below the testa. In a first stage the bran is abrasively removed in a vertical grinding machine, and in a second stage by frictional polishing. By this means it should be possible to drastically reduce the steep times after moistening prior to the milling. The penetration time of the water for softening should be only c. 30 minutes. At the same time pollutants are reduced. The grinding does not allow the germ to be removed.
Several methods are also known where the brewer's grain is dehusked or shelled after a malting or a kiln drying, e.g., according to DE-A-4428987, DE-A-3211332 or WO-A-01/21012.